HELP - Sump Ejector Pump is Emptying Toilet Plus Water Backing Up Into Shower

Really need some help here. For a while now, we noticed that whenever we wash a load of clothes, our toilet gurgles loudly and all the water in the bowl drains out. This has been going on for months, and we never did anything about it, as a friend of ours who works in plumbing said that it wasn't anything that needed immediate attention - it was just an inconvenience of sorts. All we have to do to get water in the toilet bowl again is flush it, and all is well. BUT, tonight, something else happened. As the washing machine was doing its thing, the toilet began to gurgle and empty out as usual, but this time I noticed the gurgling was much louder, and also this time water backed up into our bathtub at the same time the toilet bowl was emptying out. What is going on here? When we initially checked on this with our friend, he said that we needed something called a "SureVent" installed on our vent pipe. Let me add that the ONLY thing our sump pump ejector is used for is the washing machine. We do not have a basement that floods or anything like that. This is strictly an ejector pump. Would appreciate any and all feedback. Thanks!

i think by "it" neal means a roof vent immediatly down stream from pump. That "sure vent" or other maker's similar product would be a stop gap measure or if there is no way to properly vent that line. The back up into tub hints that the bathroom has venting problems and/or that the line past the tub is clogged. Many new washer do not have a lint filter anymore, that's all well and good for newer drain lines, but the lint can build up in older lines, combined with grease from kitchen and bath lines a clog can slowly build up. i have kitchen sink and dishwasher that drains down to washer connection, had sporadic clogs, got new washer with no lint trap, clog became almost annual hassle.

What else drains into the line before or shortly past that tub and toilet?

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